There is increasing evidence that the neurologic system is capable of modulating a wide range of immunologic responses including certain inflammatory processes on the skin. It has been proposed that secreted neuropeptides such as substance P (SP) may mediate these neuro-cutaneous interactions. Recent studies in our laboratory suggest that SP can specifically activate keratinocytes to secrete IL-1. This is the first evidence that cutaneous neuropeptides may mediate inflammatory events on the skin by specifically inducing epidermal keratinocytes to secrete immunologic cytokines. This proposal will address the role of SP activated kerintocytes in neuro-cutaneous inflammation. The long term objective of our program is to determine how the neurologic system may modulate inflammatory and immune processes in the skin. The specific hypothesis to be tested in this proposal is that the cutaneous neuropeptide SP may directly interact with keratinocytes to modulate: keratinocyte cytokine production, class II MCH/ICAM-1 expression, and proliferation. In this study we will focus on the effect of SP on keratinocyte IL-1, IL-6, and TGFalpha because of their proposed role in the pathogenesis of inflammatory skin diseases such as psoriasis. The specific aims of this project are: [1] to examine the effect of SP on the production of IL-1, IL-6, and TGFalpha in human keratinocytes, [2] to characterize the keratinocyte SP receptor, [3] determine if SP can modulate keratinocyte class II MHC and ICAM-1 expression [4] to determine if SP can modulate keratinocyte proliferation, [5] to determine if increased SP and SP binding are detected in active psoriatic skin lesions. The experimental design/methods of this project are: [i] to examine the effect of SP on keratinocyte IL-1, IL-6, and TGFalpha production (transcription, IL-1 mRNA stability, and secretion) by nuclear run on analysis, actinomycin D mRNA t1/2 studies, and ELISA and cytokine bioassays, [ii] to evaluate SP structural elements critical for cytokine production using a series of truncated N- and C- terminal SP peptide fragments, [iii] to characterize keratinocyte SP receptors by measuring 125I-SP keratinocyte specific binding, receptor number, kd, and size by Scatchard analysis and ligand affinity binding studies, [iv] to examine the effect of SP on keratinocyte class II MHC and ICAM-1 expression by FACS analysis, [v] to measure the effect of SP on keratinocyte proliferation by 3H-TdR incorporation (confirmed by cell counts), [vi] to distinguish primary versus secondary effects of SP on keratinocyte activation by specific blocking antibodies and anti-sense oligionucletides, [vii] to assess SP and SP receptor binding levels by immunohistochemistry techniques and 125I-SP quantative receptor autoradiography respectively. This project will lead to new important information regarding the role of cutaneous neuropeptides in the pathogenesis of neurogenic inflammation in the skin.